Impact of molecular (DNA) testing on determination of parentage.

OBJECTIVE: To examine changes in parentage testing practices since the introduction of DNA polymorphisms. METHODS: Comparison of data from American Association of Blood Banks (AABB) annual questionnaires and the responses of participants to AABB-College of American Pathologists proficiency test panels. RESULTS: DNA polymorphisms have led to a complete change in the technical methods used by parentage testing laboratories. CONCLUSIONS: The widespread use of DNA methods has increased the power of the information routinely provided to the courts in cases of disputed paternity, to agencies needing information about relatedness, and to the individuals who are tested.

Improving the safety of transfusion therapy.

Enormous strides have been made to reduce the risk of transfusion-transmitted disease. Additional tests to eliminate transfusion-transmitted disease are costly, in terms of both health care resources and availability of volunteer donors. Future improvements in safety probably will require postdraw treatment of blood and components and the use of pharmacologic agents as a substitute for transfusion.

Long-term follow-up of blood donors with indeterminate human immunodeficiency virus type 1 results on Western blot.

BACKGROUND: At present, tens of thousands of United States blood donors who are at low risk for human immunodeficiency virus type 1 (HIV-1) infection are indefinitely deferred. These persons are repeatably reactive for HIV-1 antibody in enzyme immunoassay (EIA) and are indeterminate in Western blot. STUDY DESIGN AND METHODS: To determine the significance and persistence of anti-HIV-1 reactivity in plasma from volunteer blood donors with HIV-1-indeterminate Western blots, 66 donors were retested for HIV-1 antibody by the same manufacturers' EIA and Western blot 5 to 7 years after the initial Western blot. In addition, donors' peripheral blood mononuclear cells were tested by polymerase chain reaction (PCR) for HIV-1 DNA gag sequences. RESULTS: Thirty-five (53%) of 66 donors were still repeatedly reactive for HIV-1 on EIA and indeterminate on Western blot, 23 (35%) were negative on EIA and indeterminate on Western blot, 7 (11%) were negative in EIA and Western blot, and 1 (2%) was repeatedly reactive on EIA and negative on Western blot. Donors with persistently indeterminate Western blots had a band pattern nearly identical to that on the original Western blot. No donor was positive in Western blot, p24 antigen, or PCR testing. No donor had signs or symptoms of HIV-1 infection. CONCLUSION: Long-term follow-up of Western blot-indeterminate blood donors does not reveal evidence of HIV-infection. A mechanism to return these donors to the donor pool should be considered.

Evaluation of clinical and laboratory aspects of antibody tests for detection of hepatitis C virus infection in blood donors and recipients from a low-risk population.

BACKGROUND: When the first-generation enzyme immunoassay (EIA) for detection of antibody to hepatitis C virus (anti-HCV) was approved in May 1990, blood banking agencies recommended testing of all components in inventory. In many cases, one or more components from these units had already been transfused. STUDY DESIGN AND METHODS: Donors that reacted in first-generation EIAs and recipients of their components were identified, and anti-HCV test methods (including first-generation EIA, second-generation EIA, and recombinant immunoblot assay [RIBA]) were evaluated. RESULTS: Of 66 donors identified as anti-HCV-positive by first-generation EIA, 17 were positive in second-generation EIA. Of these 17, 9 reacted in RIBA; 6 of these showed evidence of HCV infection in polymerase chain reaction (4) and/or probable transmission of HCV to a transfusion recipient (3). Of the 48 specimens that were positive in first-generation EIA and negative in second-generation EIA, only 1 was positive in RIBA; serum was not available for polymerase chain reaction testing, and there were no living transfusion recipients in whom to assess evidence of transmission of HCV. CONCLUSION: This study documents the low predictive value of EIAs for anti-HCV in a low-prevalence blood donor population and emphasizes the need for additional testing to confirm the specificity of samples that react in the screening tests.

A novel variant of the human blood group K1 antigen.

A discrepancy in duplicate anti-K1 typing in a parentage case led to the discovery of an unusual K1 blood group antigen. Red blood cells from the propositus (JC) express a rare variant of the K1 antigen that is detectable by only 8 of 72 sera containing anti-K1. Absorption and elution studies using reactive anti-K1 confirmed the presence of a K1 antigen. Nonreactive anti-K1 was not absorbed by or eluted from JC's red blood cells. Red cells from 3 of the propositus's siblings also had the variant K1 antigen. The variant antigen exhibited qualitative as well as quantitative differences as compared to normal K1, and we have named it K1var.

The 1990 Comprehensive Blood Bank Surveys of the College of American Pathologists.

The performance of participants on the 1990 Comprehensive Blood Bank Surveys of the College of American Pathologists was consistent with the high quality of past surveys. The surveys include challenges in ABO and Rh typing, crossmatching, transfusion decisions, unexpected antibody detection and identification, and supplemental questions to assess contemporary practices. As in previous years, a recurrent serologic problem has been the reporting of antibodies not present in serum (anti-E in Set J-B, and anti-K in Set J-D). Such overidentification of antibodies has little implication for transfusion safety and may, in fact, represent an artifact of the survey's samples and reporting practices.

Safety in transfusion practices. Preventing infectious complications.

The benefits of transfusion therapy must always be weighed against the unavoidable chance of an infectious complication. Strategies to minimize the infectious risks inherent in the use of human blood and blood components can be categorized under four general headings: donor selection, testing, appropriate use, and follow-up and reporting of complications. The application of these strategies in the context of their role in the prevention of some of the infectious complications of transfusion therapy is discussed in this article.

The magnitude and origin of European-American admixture in the Gila River Indian Community of Arizona: a union of genetics and demography.

Complementary genetic and demographic analyses estimate the total proportion of European-American admixture in the Gila River Indian Community and trace its mode of entry. Among the 9,616 residents in the sample, 2,015 persons claim only partial Native American heritage. A procedure employing 23 alleles or haplotypes at eight loci was used to estimate the proportion of European-American admixture, m(a), for the entire sample and within six categories of Caucasian admixture calculated from demographic data, md. The genetic analysis gave an estimate of total European-American admixture in the community of 0.054 (95% confidence interval [CI] .044-.063), while an estimate from demographic records was similar, .059. Regression of m(a) on md yielded a fitted line m(a) = .922md, r = .959 (P = .0001). When total European-American admixture is partitioned between the contributing populations, Mexican-Americans have provided .671, European-Americans .305, and African-Americans .023. These results are discussed within the context of the ethnic composition of the Gila River Indian Community, the assumptions underlying the methods, and the potential that demographic data have for enriching genetic measurements of human admixture. It is concluded that, despite the severe assumptions of the mathematical methods, accurate, reliable estimates of genetic admixture are possible from allele and haplotype frequencies, even when there is little demographic information for the population.

The 1988 comprehensive blood bank survey of the College of American Pathologists.

An average of 2211 laboratories reported results in this comprehensive blood bank survey. In general, the participant performance remains strong in ABO and D typing, unexpected antibody detection and identification, crossmatching, and antigen identification. However, certain samples achieved less than the usual performance levels. In one sample, anti-C, which was not present, was reported by many participants. In a third sample, only 90% of the participants correctly recorded that no antibody was detectable. Two cross-match challenges did not reach the required participant consensus for grading purposes. The ungraded samples and the supplementary questions provide mock clinical situations and are used to determine current practices and procedures in transfusion medicine. The results of these studies and the participant responses are included.

Fetomaternal hemorrhage: incidence, risk factors, time of occurrence, and clinical effects.

Most women have only very small amounts of fetal blood in their circulations following pregnancy and delivery: the volume is less than 0.5 mL of whole blood in 93 percent of women, less than 1 mL in 96 percent, and less than 2 mL in 98 percent. FMH of 30 mL or more occurs in just 3 of 1000 women. When the FMH was 150 mL or more, 15 of 41 infants did not survive Rh-negative women with FMH of more than 30 mL of Rh-positive whole blood are at increased risk of Rh immunization, and thus the outcome of their future pregnancies also may be affected. ABO-compatible fetal red cells that have entered the maternal circulation have a life span similar to that of adult cells. ABO-incompatible fetal red cells may be cleared rapidly, but in some cases they circulate for weeks. Most FMHs of 30 mL or more occur before labor, delivery, or cesarean section. The majority occur with minimal clinical signs and symptoms in apparently normal pregnancies. The identification of postpartum Rh-negative women who have 30 mL or more of Rh-positive fetal blood in their circulation is important so that sufficient RhIG for immune suppression can be administered. It appears that more than one-half of women with FMH of 30 mL or more would not be identified if protocols were adopted to test only women in pregnancies considered to be at high risk.

Human immunodeficiency virus type 1 proficiency testing. The American Association of Blood Banks/College of American Pathologists Program.

The American Association of Blood Banks/College of American Pathologists Viral Marker Survey program added samples to evaluate participant performance with test systems for the detection of antibodies to human immunodeficiency virus type 1 in 1985. On the 80 challenges sent through April 1989, the major problem observed with enzyme immunoassay testing was unexpected reactivity on samples that did not contain anti-human immunodeficiency virus type 1. One manufacturer's testing system accounted for most of the specificity problems. The sensitivity of the enzyme immunoassay for anti-human immunodeficiency virus type 1 is close to 99%, based on the multiple reactive samples used on the 16 panels. Between 1985 and 1989, there was a 14-fold increase in participants reporting Western blot results. The introduction of a licensed system for Western blots increased the number of samples that contained antibody to human immunodeficiency virus type 1 interpreted as indeterminate. Answers to supplementary questions showed that the rate of repeatably reactive and confirmed positives on blood donors dropped to less than 0.1%.

Microcomputer-generated antigen panel worksheets.

Many antibody identifications require testing with cells of rare or uncommon phenotypes. To expedite the resolution of these identifications, we developed a microcomputer database using Lotus 123 to enter antigen phenotypes from our frozen cell inventory. Data is entered into a customized screen input form and automatically copied to the database The use of an input form protects the database from inadvertent errors made while entering data. The database can be searched for any combination of red cell phenotypes. When found, the selected cells are extracted tu a predesigned worksheet. Panel worksheet forms are created with Allways, a software program used in conjunction with Lotus 123, Allways is specifically designed to generate quality printouts with a laser printer. The program has many formatting features that simplify horizontal and vertical ruling for the worksheet. In addition, the program provides degrees of shading to highlight specific antigens or entire columns or rows of information. Once the worksheet template has been designed, it is automatically saved with the database file. More than one worksheet template can be stored in the database file. This program reduces the amount of time spent searching through records to find the necessary cells for testing, It also reduces potential error in hand copying antigen phenotypes to a worksheet. This application can also he used for HLA panels.

Genetic structure of Mennonite populations of Kansas and Nebraska.

We describe the gene frequency distributions for 29 different blood group, serum, and erythrocytic proteins for three Mennonite communities from Kansas and Nebraska and compare their gene frequencies with those of Amish, Hutterite, and Mennonite populations using the topological method of Harpending and Jenkins (1973). Subdivision of these communities into congregations reveals that the "fission-fusion'h model best characterizes the relationship between the genetic patterns and historical events. These Mennonite populations, although reproductively isolated at the turn of this century, are presently entering the mainstream of US rural culture.